Q. A force F = (2.0 N/m^2)x^2i is applied to a particle initially at rest in the xy plane. Find the work done by this force on the particle and the final speed of the particle as it moves along a path that is (a) in a straight line from point (2.0 m, 2.0 m) to point (2.0 m, 7.0 m) and (b) in a straight line from point (2.0 m, 2.0 m) to point (5.0 m, 6.0 m). The given force is the only force doing work on the particle.

Q. A dolphin in 25 degree C sea water emits a sound direct toward the bottom of the ocean 126 m below. How much time passes before it hears an echo?